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AP EAMCET2001PhysicsCapacitance

A 20 ~F capacitor is charged to 5 ~V and isolated. It is then connected in parallel with an uncharged 30 ~F capacitor. The decrease in the energy of the system will be

Options

  1. A25 ~J
  2. B100 ~J
  3. C125 ~J
  4. D150 ~J

Correct answer

D. 150 ~J

Step-by-step solution

C _ s =20 ~F , V=5 volt, F_x=30 ~F Decrease in energy, U= 1 2 C₁ C₂ C₁+C₂ (V₂-V₂ )^2 aligned & = 1 2 20 30 20+30 (5-0)^2 & = 300 50 25=150 ~J aligned

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